Biodegradable polymers have very unique properties, such as their generally good biocompatibility, degradationity in the body, degradation products can be absorbed by the body or excreted through the body's normal physiological pathway, and is widely used in various biomedical fields, such as surgical sutures, bone fixation devices, bio-tissue engineering scaffold materials, and drug-controlled release carrier et. al. Among them, synthetic biodegradable polymers are of particular interest due to their low immunogenicity, their properties such as degradation and mechanical properties, and the like, can be easily controlled. Synthetic biodegradable polymers are mainly aliphatic polyester, polycarbonate, polyamino acid, polyphosphate, polyanhydride, poly orthoester and so on. Among them, polycarbonates such as polytrimethylene cyclic carbonate (PTMC), aliphatic polyester such as polyglycolide (PGA), polylactide (PLA), lactide-glycolide copolymer (PLGA), polycaprolactone (PCL) and so on are the most commonly used biodegradable polymers, has got the permission of the US Food and Drug Administration (FDA).